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121.
利用波长为266nm的激光光解CHBr3产生CH自由基,其与NO反应作为NCO自由基的来源.在298K,总压2660Pa的条件下,采用激光诱导荧光的方法,研究了NCO自由基与SO2、CS2的反应.得到了NCO自由基与SO2、CS2双分子反应速率常数分别为(1.8±0.3)×10-11和(3.1±0.4)×10-12cm3·molecule-1·s-1.对这两个反应在B3LYP/6-31 G(d)的水平上进行理论研究的结果表明,NCO自由基与SO2、CS2的反应是加成反应,其机理是NCO自由基中的N原子攻击反应物的中心原子,得到加成产物. 相似文献
122.
A new pulse sequence is proposed for the determination of scalar coupling correlation in small- and medium-sized organic compounds. The method uses a combination of the double pulsed field gradient spin-echo (DPFGSE) and the selective population transfer (SPT) techniques and is shown to be useful in the analysis of complex spectra with many overlapped signals. The usefulness of this method in the structural elucidation of natural substances is demonstrated using strychnine and digitoxin as examples. 相似文献
123.
124.
N-乙酸基取代四氮杂大环及其镧系配合物的热力学研究 总被引:2,自引:0,他引:2
用pH电位滴定法分别在25±0.1℃,40±0.1℃和80±0.1℃,0.5mol/LKNO3水溶液中测定了H_4L(5,7,12,14-四甲基-1,4,8,11-四氮杂环十四烷-N',n",N"',N""-四乙酸)的逐级质子化常数和焓值。又在40±0.1℃和80±0.1℃条件下测定了H4L与镧系金属离子(La~(3+),Nd~(3+),pr~(3+),Sm~(3+),Eu~(3+),Gd~(3+),Dy~(3+),Yb~(3+))配合物的稳定常数。结果表明:配合物稳定性高。 相似文献
125.
Inorganic-organic hybrids have been synthesized by incorporation of the inorganic component of Ti(OC2H5)4 into the organic polymer of ethyl cellulose. The inorganic-organic hybrids did not dissolve in toluene used as a solvent for the starting materials. The ethanol was formed as a by-product of the alcoholysis condensation reaction between Ti(OC2H5)4 and ethyl cellulose. These results suggest that ethoxy groups of Ti(OC2H5)4 react with hydroxy groups of ethyl cellulose to form cross-linking bonds of –O–Ti–O–. The reaction of Ti(OC2H5)4 with ethyl cellulose was further investigated by Fourier transform infrared (FT-IR) spectroscopy. The FT-IR spectroscopic experiments revealed that the Ti–O bond state of Ti(OC2H5)4 was changed by refluxing a toluene solution of Ti(OC2H5)4 with ethyl cellulose. The inorganic-organic hybrids have an interesting dielectric property; their dielectric constant is higher than that of ethyl cellulose and that of a simple mixture of TiO2 and ethyl cellulose. 相似文献
126.
固定pH滴定法测定弱酸弱碱性药物 总被引:8,自引:0,他引:8
报道一种水溶液吕测定弱酸弱碱性药物的新型滴定分析方法-固定pH滴定法,其理论基础是弱酸弱碱在水溶液中各种存在形式的分布系数在pH值固定时为常数,对甲硝唑,盐酸美西律等离散常数在10^-8至10^-11范围内的7种弱酸弱碱性药物进行测定。结果与药典法吻合,回收率在99.4%~100.6%,方法简便,快速,准确,制剂中的赋形剂及色物不影响测定。 相似文献
127.
Masahiro Manabe Toshihiro Ochi Hideo Kawamura Hajime Katsu-ura Masaki Shiomi Mandeep Singh Bakshi 《Colloid and polymer science》2005,283(7):738-746
The partial molar volumes (Va) of 1-alkanols (carbon number, m=5, 6, 7) in - and -cyclodextrin (CD) solutions at 5.00 mmol kg–1 have been determined as a function of alkanol concentration (Ca) between 293.2 and 308.2 K by using a dilatometer. It has been observed that with an increase in Ca, Va increased in -CD solution but decreased in -CD solution, asymptotically to a value of Va in CD-free water. The dependence of Va on Ca provided the binding constant (K) of 1:1 complex, the volume change in complex formation, and the partial molar volume of complex itself. The complex formation mechanism has been discussed on the basis of these values and their carbon number dependences in the respect of geometric behavior, hydrophobic interaction, and van der Waals interaction. It is concluded that the CD cavity in water is not rigid but flexible for fitting in nicely with guest molecule. 相似文献
128.
Organic sulfonyl fluorides are of interest owing to their insecticidal, germicidal and enzyme inhibitory properties. In the current work, synthesis of p-toluenesufonyl fluoride was accomplished by reacting p-toluenesulfonyl chloride with solid potassium fluoride using PEG-400 as a catalyst under solid-liquid phase transfer catalysis (S-L PTC) at 30 °C. p-Toluenesulfonyl fluoride is used as peroxygen bleach activator. It also finds use in the treatment of Alzheimer's disease. The mechanism is based on homogeneous solubilization of solid. PEG forms a complex with metal cation which associates with the nucleophile and it participates in SN2 type reactions. The reaction is intrinsically kinetically controlled. A complete theoretical analysis is done to determine both the rate constant and equilibrium constant from the same set of data. The activation energy and Gibbs free energy are also calculated. 相似文献
129.
V. E. Schneider E. E. Tornau A. A. Vlasova A. A. Gurskas 《Journal of inclusion phenomena and macrocyclic chemistry》1985,3(3):235-242
Clathrate thermodynamic stability conditions and the phase transitions associated with either the orientational ordering of the guest molecules or with the condensation of the guest molecules in the host lattice are investigated by means of the common microscopic model. The theory proposed describes the thermodynamic properties of -hydroquinone (Q
) clathrates. The dielectric constant (T) was measured experimentally inQ
·CH3OH andQ
·SO2 in the temperature range from 4.2 to 300 K and the phase transitions were found. It is shown that the theory qualitatively explains the experimental data obtained.Dedicated to Professor H. M. Powell. 相似文献
130.